Motor of compressor and refrigeration cycle apparatus

ABSTRACT

A compressor includes: a stator core including a plurality of teeth around which an aluminum winding wire is wound in a concentrated manner; a rotor core disposed on an inner diameter side of the stator core and including a plurality of magnet insertion holes; and a plurality of ferrite magnets inserted in the magnet insertion holes, in which when a width of a winding wire portion formed in each of the teeth is represented as A, a length in an axis direction of the stator core is represented as L, and the number of slots is represented as S, the stator core has a shape that satisfies a relation of 0.3&lt;S×A÷L&lt;2.2.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of U.S. utility application Ser. No. 15/500,609 filed on Jan. 31, 2017, which is a U.S. national stage application of PCT/JP2014/072755 filed on Aug. 29, 2014, the contents of which are incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to a motor of a compressor that, while converting a refrigerant subjected to a low temperature and a low pressure into a refrigerant subjected to a high temperature and a high pressure, and circulates the resultant refrigerant, and a refrigeration cycle apparatus including the compressor.

BACKGROUND

A conventional motor disclosed in Patent Literature 1 listed below has a configuration in which a cylindrical permanent magnet is disposed on an outer circumference of a rotor core and a magnetic tube made of stainless steel is further disposed on an outer circumference of the permanent magnet to prevent significant demagnetization of the permanent magnet due to a high temperature. Magnetic resistance of a magnetic circuit viewed from the permanent magnet is reduced by the magnetic tube provided between the permanent magnet and a stator, a residual magnetic flux density at an operating point of the permanent magnet at the time of armature reaction increases, and a magnetic flux reaching a stator core from the permanent magnet increases. Therefore, the conventional motor disclosed in Patent Literature 1 listed below can prevent demagnetization of the permanent magnet and prevent a reduction of its output even when the permanent magnet has a high temperature and armature reaction is exerted.

PATENT LITERATURE

-   Patent Literature 1: Japanese Patent Application Laid-open No.     H7-322539

However, because a magnetic permeability of stainless steel constituting the magnetic tube is lower than a magnetic permeability of silicon steel or Armco ion used for the rotor core and the stator core, the configuration taught by Patent Literature 1 is unsuitable for improving the motor efficiency. On the other hand, in a compressor, during one revolution of a rotor, a compression torque varies according to a rotational position of the motor, and the maximum value of the compression torque may be three times an average torque depending on an operation condition. In a motor of a compressor, demagnetization of a rotor magnet depends on a peak current flowing at the time of the maximum compression torque. Therefore, a motor of a compressor needs to conform to a specification with demagnetization resistance considered more significantly than a motor represented by Patent Literature 1 mentioned above, that is, a motor used for a mechanism including no load change.

SUMMARY

The present invention has been achieved in view of the above circumstances, and an object of the present invention is to provide a motor for a compressor that can improve demagnetization resistance while suppressing a reduction in motor efficiency.

In order to solve the above-mentioned problems and achieve the object, the present invention provides a motor of a compressor comprising: a stator core including a plurality of teeth and a plurality of slots formed between the teeth, an aluminum winding wire being wound around the teeth in a concentrated manner; a rotor core disposed on an inner diameter side of the stator core and including a plurality of magnet insertion holes; and a plurality of ferrite magnets inserted into the magnet insertion holes, wherein when a width of a winding wire portion formed in each of the teeth is represented as A, a length in an axis direction of the stator core is represented as L, and the number of the slots is represented as S, the stator core has a shape that satisfies a relation of 0.3<S×A÷L<2.2.

According to the present invention, an advantageous effect is yielded in that it is possible to improve demagnetization resistance while suppressing a reduction in motor efficiency.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a side view of a motor of a compressor according to a first embodiment of the present invention.

FIG. 2 is a sectional view of a stator and a rotor illustrated in FIG. 1 taken along a line in the direction by arrows A-A.

FIG. 3 is a configuration diagram of a refrigeration cycle apparatus having the compressor illustrated in FIG. 1 mounted thereon.

FIG. 4 is a chart illustrating variation in a compression torque of the compressor.

FIG. 5 is a chart illustrating rates of copper losses of a copper wire and an aluminum wire.

FIG. 6 is a chart illustrating relations between a magnet temperature and a coercive force.

FIG. 7 is a diagram illustrating specific heats of a ferrite magnet and a rotor core.

FIG. 8 is an illustration representing heat transmitted to inside of the rotor core.

FIG. 9 is a sectional view of a surface-magnet rotor.

FIG. 10 is a partially enlarged view of teeth.

FIG. 11 is a sectional view of the teeth illustrated in FIG. 10 taken along a line in the direction by arrows a-a.

FIG. 12 is a chart illustrating a copper loss obtained by actual measurement.

FIG. 13 is a side view of a motor of a compressor according to a second embodiment of the present invention.

FIG. 14 is a side view of a motor of a compressor according to a third embodiment of the present invention.

FIG. 15 is a sectional view of a rotor illustrated in FIG. 14 .

FIG. 16 is a view illustrating a modification of the rotor illustrated in FIG. 14 .

DETAILED DESCRIPTION

A motor of a compressor and a refrigeration cycle apparatus according to embodiments of the present invention will be described below in detail with reference to the drawings. The present invention is not limited to the embodiments.

First Embodiment

FIG. 1 is a side view of a motor of a compressor according to a first embodiment of the present invention, FIG. 2 is a sectional view of a stator and a rotor illustrated in FIG. 1 taken along a line in the direction by arrows A-A, and FIG. 3 is a configuration diagram of a refrigeration cycle apparatus having the compressor illustrated in FIG. 1 mounted thereon.

A compressor 100 illustrated in FIG. 1 includes a stator 1 disposed on an inner circumferential surface of a frame (not illustrated), a rotor 2 disposed on an inner diameter side of the stator 1 with a clearance 8 located therebetween, and a compression unit 3 to which a shaft 7 penetrating the rotor 2 is connected. Discharge holes 3 a for discharging a high-pressure refrigerant compressed by the compression unit 3 are formed on an upper portion of the compression unit 3.

The stator 1 and the rotor 2 constitute a motor of the compressor 100. The stator 1 is fixed to the inner circumferential surface of the frame (not illustrated) by press fitting, shrinkage fitting or freeze fitting. The shaft 7 is held in a state such that the shaft can rotate by bearings (not illustrated) provided on an upper part and a lower part of the compressor 100.

The stator 1 illustrated in FIG. 2 is composed of an annular stator core 5 constructed of a number of electromagnetic steel sheets each having been formed in a specific shape by a stamping process, and having been stacked on top of another in an axis direction, and an aluminum winding wire 6 to which external electric power is supplied.

The stator core 5 has an annular back yoke 5 a, and a number of teeth 5 b that are arranged on an inner diameter side of the back yoke 5 a at regular intervals in a rotation direction and that extend from the back yoke 5 a toward a center of the stator core 5.

Each of the teeth 5 b has a winding wire portion 5 b 1 around which the aluminum winding wire 6 is wound, and an umbrella-shaped tooth end portion 5 b 2 that is formed on an inner diameter side of the corresponding tooth 5 b and has a facing surface 5 e facing the rotor 2, which extends in the rotation direction.

A number of slots 5 d are also formed on the stator core 5, which are spaces delimited by the back yoke 5 a, the winding wire portions 5 b 1 and the tooth end portions 5 b 2.

In the illustrated example, nine teeth 5 b are formed. The width in the rotation direction of the winding wire portion 5 b 1 is constant from the back yoke 5 a to the tooth end portion 5 b 2. The aluminum winding wire 6 that generates a rotating magnetic field is wound around the winding wire portion 5 b 1 in a concentrated winding method. In FIG. 2 , only the aluminum winding wire 6 that is wound around one winding wire portion 5 b 1 is illustrated and illustrations of the aluminum winding wire 6 on the other portions are omitted.

The rotor 2 includes a cylindrical rotor core 2 a formed by stacking a number of electromagnetic steel sheets each having been formed in a specific shape by a stamping process, and having been stacked on top of another in the axis direction, a number of magnet insertion holes 2 b provided at regular intervals in the rotation direction in correspondence with the number of magnetic poles and having a curved shape protruding to a radially inner side, ferrite magnets 2 c each having a shape corresponding to the shape of the magnetic insertion hole 2 b and inserted into the magnetic insertion holes 2 b, respectively, and a shaft insertion hole 2 d formed at a center about a radial direction of the rotor core 2 a.

The shaft 7 is fixed to the shaft insertion hole 2 d by press fitting, shrinkage fitting or freeze fitting. The magnet insertion holes 2 b extend in the axis direction, and six ferrite magnets 2 c are inserted into the magnet insertion holes 2 b, respectively, in the illustrated example.

The clearance 8 is formed between an outer circumferential surface of the rotor 2 and the tooth end portions 5 b 2. When the aluminum winding wire 6 is subjected to electric conduction, a rotating magnetic field is generated between the rotor 2 and the stator 1, and thereby the rotor 2 is rotated.

A refrigeration cycle apparatus 30 illustrated in FIG. 3 includes the compressor 100 illustrated in FIG. 1 , a control circuit 31, a temperature sensor 32, a condenser 33, a decompression device 34, an evaporator 35, a bypass circuit 36, an on-off valve 37, and anther decompression device 38.

The control circuit 31 controls the on-off valve 37 based on a detection result of the temperature sensor 32. The temperature sensor 32 is provided near a gas outlet of the compressor 100 to detect a temperature of a refrigerant flowing through the gas outlet. The bypass circuit 36 constituted by the decompression device 38 and the on-off valve 37 that are connected in series is interposed between a liquid refrigerant outlet of the condenser 33 and a gas inlet of the compressor 100. The refrigeration cycle apparatus 30 is suitable for an air conditioner.

An operation is described below. High-temperature and high-pressure refrigerant gas compressed by the compressor 100 exchanges heat with air and condenses to become a liquid refrigerant in the condenser 33. The liquid refrigerant expands in the decompression device 34 to become low-temperature and low-pressure refrigerant gas. The low-temperature and low-pressure refrigerant gas sucked in the compression unit 3 illustrated in FIG. 1 is compressed in the compression unit 3 based on rotation of the rotor 2 to have a high temperature and a high pressure again. The high-temperature and high-pressure refrigerant gas passes through the clearance 8 between the stator 1 and the rotor 2 or the slots 5 d, and is discharged from a discharge pipe (not illustrated) formed on the compressor 100. In this manner, in the refrigeration cycle apparatus 30, the refrigerant circulates through the compressor 100, the condenser 33, the decompression device 34 and the evaporator 35 in this order, and returns again to the compressor 100.

FIG. 4 is a chart illustrating variation in a compression torque of the compressor. Because the compressor 100 performs a compression operation, the compression torque changes while the rotor 2 rotates one revolution as illustrated in FIG. 4 . Assuming that an average torque Ta is 100%, the maximum value of the compression torque may reach 300% that is three times the average torque Ta depending on an operation condition.

In the motor used in the compressor 100, demagnetization of a rotor magnet depends on a peak current flowing at the time of the maximum compression torque. Therefore, the motor used in the compressor 100 needs to conform to a specification with demagnetization resistance considered more significantly than a motor used in a mechanism including no load change.

For the motor of the compressor 100 according to the first embodiment, the aluminum winding wire 6 that is a winding wire made of aluminum having a lower electric conductivity than a copper wire used as a generally used winding wire, and the ferrite magnets 2 c having a positive temperature coefficient of coercive force are used to improve the demagnetization resistance.

FIG. 5 is a chart illustrating rates of copper losses of a copper wire and an aluminum wire, FIG. 6 is a chart illustrating relations between the magnet temperature and the coercive force, FIG. 7 is a chart illustrating specific heats of the ferrite magnet and the rotor core, FIG. 8 is an illustration representing heat transmitted to inside of the rotor core, and FIG. 9 is a sectional view of a surface-magnet rotor.

As illustrated in FIG. 5 , assuming that the copper loss of a copper wire is 100%, the copper loss of an aluminum wire reaches 160% that is 1.6 times that of the copper wire. Therefore, when a winding wire to be wound around the stator 1 is changed from a copper wire to an aluminum wire, heat corresponding to a difference in copper loss between the copper wire and the aluminum wire is generated in the stator 1 illustrated in FIG. 2 .

Meanwhile, the temperature coefficient of coercive force of the ferrite magnets 2 c is positive while the temperature coefficient of coercive force of a rare-earth magnet is negative as illustrated in FIG. 6 . That is, the ferrite magnets 2 c have characteristics that the coercive force increases with increases in magnet temperature. Because the resistance to a demagnetizing field is increased and the reliability is enhanced when the coercive force increases, it is desirable that the coercive force is higher.

A material having a lower specific heat than that of the ferrite magnets 2 c is used for the embedded-magnet rotor core 2 a as illustrated in FIG. 7 . When a material having a lower specific heat is used for the embedded-magnet rotor core 2 a, heat generated by the aluminum winding wire 6 can be transmitted to the ferrite magnets 2 c more effectively than a surface-magnet rotor core 20 a illustrated in FIG. 9 .

This matter is described specifically. When a surface-magnet rotor 20 illustrated in FIG. 9 is set in the stator 1 illustrated in FIG. 2 , heat transmitted from the teeth 5 b transmits toward inside of the magnets 20 c gradually from outer circumferential surfaces on a radially outer side of the magnets 20 c arranged on an outer circumferential surface of the rotor core 20 a in the rotor 20. That is, because the heat from the teeth 5 b transmits only to the outer circumferential surfaces of the magnets 20 c in the rotor 20, the heat is not easily transmitted to a radially inner side of the magnets 20 c.

A number of arrows “a” and “b” in FIG. 8 schematically show paths of heat transmitted to the rotor core 2 a. First, in FIG. 2 , heat generated by the aluminum winding wire 6 transmits to the rotor core 2 a via the facing surfaces 5 e of the tooth end portions 5 b 2, the clearance 8, and the outer circumferential surface of the rotor core 2 a in this order. Heat denoted by the arrows “a” in FIG. 8 of the heat transmitting to the rotor core 2 a transmits to the ferrite magnets 2 c from portions on a radially outer side of the corresponding magnet insertion holes 2 b. On the other hand, heat denoted by the arrows “b” of the heat transmitting to the rotor core 2 a passes through between adjacent ones of the magnet insertion holes 2 b and transmits to the ferrite magnet 2 c via portions on a radially inner side of the magnet insertion holes 2 b.

In this manner, when a material having a lower specific heat than that of the ferrite magnets 2 c is used in the embedded-magnet rotor core 2 a, heat generated by the aluminum winding wire 6 can transmit to both the radially outer side and the radially inner side of the ferrite magnets 2 c. That is, while heat transmits only to the outer circumferential surfaces on the radially outer side of the magnets 20 c in the surface-magnet rotor core 20 a, heat can be transmitted to the entire outer circumferential surfaces of the ferrite magnets 2 c in the embedded-magnet rotor core 2 a. Therefore, the rotor 2 can increase the magnet temperature more effectively than the rotor 20 and accordingly the coercive force is enhanced in the rotor 2 with increase in the magnet temperature, thereby to improve the demagnetization resistance.

Because the degree of adhesion between the aluminum winding wire 6 and the stator core 5 is higher in the concentrated winding method, use of the concentrated winding method enables the magnetic temperature to be increased more.

A configuration for improving the demagnetization resistance by increasing the temperature of the ferrite magnets 2 c has been described above. However, because the aluminum winding wire 6 has larger loss than a copper wire, there is a concern of a reduction in motor efficiency. A configuration for improving the demagnetization resistance while suppressing a reduction in motor efficiency is described below.

FIG. 10 is a partially enlarged view of the teeth, and FIG. 11 is a sectional view of the teeth illustrated in FIG. 10 taken along a line in the direction by arrows a-a. Because the resistance value of an aluminum wire is higher than that of a generally used copper wire as described above, it is important to shorten a winding length in one turn of the aluminum winding wire 6 to be wound around the teeth 5 b.

As illustrated in FIG. 10 , the tooth end portion 5 b 2 of the tooth 5 b is formed in such a manner that a width B in the rotation direction of the facing surface 5 e is larger than a width A in the rotation direction of the winding wire portion 5 b 1.

Because the magnetic flux from the rotor 2 enters the back yoke 5 a through the tooth end portions 5 b 2 and the winding wire portions 5 b 1, designs of the tooth end portions 5 b 2 and the winding wire portions 5 b 1 are important to effectively capture the magnetic flux into the back yoke 5 a.

If the width A of the winding wire portion 5 b 1 is too large, the cross-sectional area of the slots 5 d becomes small and wire winding spaces are reduced. If a fine aluminum wire is used to ensure the number of turns of the aluminum winding wire 6, the copper loss increases and the motor efficiency deteriorates.

The solid line illustrated in FIG. 11 represents an outline of the winding wire portion 5 b 1 and the dotted line illustrated in FIG. 11 represents an outline of the tooth end portion 5 b 2 viewed from a radially outer side of the stator core 5 toward a radially inner side thereof. In FIG. 11 , there are represented the width A (mm) in the rotation direction of the winding wire portion 5 b 1, the width B (mm) in the rotation direction of the tooth end portion 5 b 2, and a length in the axis direction of the stator core 5, that is, a stack thickness L (mm) of the stator core 5 are represented. In FIG. 11 , stack thicknesses of the winding wire portion 5 b 1 and the tooth end portion 5 b 2 are regarded as the stack thickness L of the stator core 5.

A winding length in one turn of a winding wire that is a length per one turn of the aluminum winding wire 6 wound around the winding wire portion 5 b 1 can be expressed as (A+L)×2. The amount of captured magnetic flux in the axis direction is increased when the stack thickness L of the stator core 5 is increased, but the amount of captured magnetic flux does not change even when the width A of the winding wire portion 5 b 1 is increased. Therefore, it is desirable that the width A of the winding wire portion 5 b 1 is narrower.

The ratio of the winding length in one turn to the stack thickness L can be defined as (A+L)×2÷L. Meanwhile, the number of the slots 5 d needs to be designed to be adapted to the magnetic flux density of the width A of the winding wire portion 5 b 1. Therefore, when the number of the slots 5 d is S, the number S of the slots 5 d has an inverse relationship to the width A of the winding wire portion 5 b 1. When this relationship is introduced into the above expression, S×A÷L is obtained.

FIG. 12 is a chart illustrating a copper loss obtained by actual measurement. In FIG. 12 , the vertical axis represents the loss increase index and the horizontal axis represents the value obtained by S×A÷L. As illustrated in FIG. 12 , when the value obtained by S×A÷L is larger than 0.3 and smaller than 2.2, that is, when the stator core 5 has a shape that satisfies a relation of 0.3<S×A÷L<2.2, a winding length in one turn effective for capturing the magnetic flux is obtained. Therefore, even when the aluminum winding wire 6 is used, wasteful copper loss is reduced, and the demagnetization resistance can be improved while a reduction in the motor efficiency is suppressed.

Second Embodiment

FIG. 13 is a side view of a motor of a compressor according to a second embodiment of the present invention. A compressor 200 illustrated in FIG. 13 has an oil separator 4 that is installed on the shaft 7 passing through an upper surface side of the rotor core 2 a and is positioned to the upper surface side of the rotor core 2 a. The configuration other than the oil separator 4 is identical to that of the compressor 100 illustrated in FIG. 1 . Parts identical to those of the first embodiment are denoted by like reference signs and descriptions thereof will be omitted, and only parts of the second embodiment different from those of the first embodiment are described below.

Dotted arrows illustrated in FIG. 13 represent paths of a refrigerant and misty lubricant oil, and solid arrows represent paths of lubricant oil liquefied by the oil separator 4. When the oil separator 4 illustrated in FIG. 13 is provided, the refrigerant compressed by the compression unit 3 is scraped above the compression unit 3 at the time of an operation of the compressor 200. The compressed refrigerant passes through the clearance 8 or the slots 5 d and reaches a discharge pipe (not illustrated). At this time, lubricant oil accumulated below the compressor 200 is scraped above the compression unit 3 in a misty state. The misty lubricant oil absorbs heat generated by the aluminum winding wire 6 when passing through the clearance 8 or the slots 5 d as illustrated by the dotted arrows, and is liquefied by the oil separator 4. The liquefied lubricant oil drops on an axial end face of the rotor 2 located below the oil separator 4 as illustrated by the solid arrows. Heat of the lubricant oil dropped on the axial end face of the rotor 2 transmits from the axial end face of the rotor 2 to the ferrite magnets 2 c. As a result, the heat generated by the aluminum winding wire 6 can be transmitted more effectively to the ferrite magnets 2 c and the demagnetization resistance is improved more.

Third Embodiment

FIG. 14 is a side view of a motor of a compressor according to a third embodiment of the present invention, and FIG. 15 is a sectional view of a rotor illustrated in FIG. 14 . In a compressor 300 illustrated in FIG. 14 , holes 2 e are formed in the rotor core 2 a while the oil separator 4 is used. Parts identical to those of the first embodiment are denoted by like reference signs and descriptions thereof will be omitted, and only parts of the third embodiment different from those of the first embodiment are described below.

The hole 2 e is formed in a dent shape extending from a face on a side facing the oil separator 4 out of two axial end faces of the rotor core 2 a toward the compression unit 3 as illustrated in FIG. 14 . The holes 2 e are provided at regular intervals in the rotation direction between adjacent ones of the magnet insertion holes 2 b and between the magnet insertion holes 2 b and the shaft insertion hole 2 d, as illustrated in FIG. 15 .

The lubricant oil liquefied by the oil separator 4 infiltrates into the holes 2 e of the rotor core 2 a located below the oil separator 4 and heat of the lubricant oil infiltrated into the holes 2 e transmits to the ferrite magnets 2 c from a radially inner side of the ferrite magnets 2 c. As a result, the heat generated by the aluminum winding wire 6 can be transmitted more effectively to the ferrite magnets 2 c and the demagnetization resistance can be improved more.

FIG. 16 is a view illustrating a modification of the rotor illustrated in FIG. 14 . In the compressor 300 illustrated in FIG. 16 , holes 2 e-1 penetrate both the axial end faces of the rotor core 2 a. Due to this configuration, the lubricant oil liquefied by the oil separator 4 can be infiltrated into the holes 2 e-1 from their upper side to heat the ferrite magnets 2 c. Furthermore, the holes 2 e-1 can also serve as flow passages of the refrigerant as shown by dotted line arrows. That is, the refrigerant infiltrated into the holes 2 e-1 from their lower side passes through the holes 2 e-1 toward their upper side and is discharged from a discharge pipe (not illustrated). As a result, the flow amount of the refrigerant in the compressor 300 is increased and the refrigeration capacity of the refrigeration cycle apparatus 30 can be improved.

The positions of the holes 2 e and the holes 2 e-1 described in the third embodiment are not limited to positions between adjacent ones of the magnet insertion holes 2 b and between the magnet insertion holes 2 b and the shaft insertion hole 2 d. For example, a number of holes can be provided at regular intervals in the rotation direction between each of the magnet insertion holes 2 b and the shaft insertion hole 2 d. Also in this configuration, the heat generated by the aluminum winding wire 6 can be effectively transmitted to the ferrite magnets 2 c. By mounting one of the compressors 100, 200 and 300 according to the first to third embodiments on the refrigeration cycle apparatus 30, the refrigeration cycle apparatus 30 with high efficiency and high reliability can be provided.

As described above, the compressors 100, 200 and 300 according to the first to third embodiments include the stator core 5 in which the aluminum winding wire 6 is wound around the plural teeth 5 b in a concentrated manner, the rotor core 2 a disposed on an inner diameter side of the stator core 5 and having the plural magnet insertion holes 2 b, and the plural ferrite magnets 2 c inserted into the plural magnet insertion holes 2 b, in which when the width of the winding wire portions 5 b 1 formed in the teeth 5 b is represented as A, the length in the axis direction of the stator core 5 is represented as L, and the number of the plural slots 5 d is represented as S, the stator core 5 has a shape that satisfies a relation of 0.3<S×A÷L<2.2. Due to this configuration, heat generated by the aluminum winding wire 6 can be transmitted to the ferrite magnets 2 c to improve the coercive force. Furthermore, because a winding length in one turn effective for capturing the magnetic flux can be obtained, wasteful copper loss is reduced even when the aluminum winding wire 6 is used, so that the demagnetization resistance can be improved while a reduction in the motor efficiency is suppressed.

Furthermore, the compressors 200 and 300 according to the second and third embodiments have the oil separator 4 installed on the shaft 7 penetrating the upper surface side of the rotor core 2 a and positioned on the upper surface side of the rotor core 2 a. This configuration enables heat of lubricant oil liquefied by the oil separator 4 to be transmitted to the ferrite magnets 2 c, thereby effectively heating the ferrite magnets 2 c.

In the rotor core 2 a of the compressor 300 according to the third embodiment, the holes 2 e or 2 e-1 that are formed between the magnet insertion holes 2 b and the shaft insertion hole 2 d and open on the oil separator 4 side are formed. Due to this configuration, heat of lubricant oil liquefied by the oil separator 4 can be transmitted to the ferrite magnets 2 c from the radially inner side of the ferrite magnets 2 c, and the ferrite magnets 2 c can be effectively heated.

Furthermore, the holes 2 e-1 according to the third embodiment penetrate the both end faces of the rotor core 2 a. Therefore, the flow amount of a refrigerant in the compressor 300 is increased, and the refrigeration capacity of the refrigeration cycle apparatus 30 can be improved.

The configurations described in the above embodiments are only examples of the configuration of the present invention and can be combined with other publicly known techniques, and a part of the configurations can be omitted or modified without departing from the scope of the present invention. 

The invention claimed is:
 1. A motor of a compressor comprising: a stator core including a plurality of teeth and a plurality of slots formed between the teeth, an aluminum winding wire being wound around the teeth in a concentrated manner; a rotor core disposed on an inner diameter side of the stator core and including a plurality of magnet insertion holes; and a plurality of ferrite magnets inserted into the magnet insertion holes, wherein when a width of a winding wire portion formed in each of the teeth is represented as A, a length in an axis direction of the stator core is represented as L, and the number of the slots is represented as S, the stator core has a shape that satisfies a relation of 0.3<S×A÷L<2.2.
 2. The motor of a compressor according to claim 1, wherein a material having a lower specific heat than that of the ferrite magnets is used for the rotor core.
 3. A refrigeration cycle apparatus comprising the compressor according to claim
 1. 4. A motor of a compressor comprising: a stator core including a plurality of teeth and a plurality of slots formed between the teeth, an aluminum winding wire being wound around the teeth in a concentrated manner; a rotor core disposed on an inner diameter side of the stator core and including a plurality of magnet insertion holes; a plurality of ferrite magnets inserted into the magnet insertion holes; and an oil separator installed on a shaft penetrating an upper surface side of the rotor core and positioned on an upper surface side of the rotor core, wherein when a width of a winding wire portion formed in each of the teeth is represented as A, a length in an axis direction of the stator core is represented as L, and the number of the slots is represented as S, the stator core has a shape that satisfies a relation of 0.3<S×A÷L<2.2, in the rotor core, holes that are formed between the magnetic insertion holes and a shaft insertion hole and each have an opening to the oil separator side are formed.
 5. The motor of a compressor according to claim 4, wherein a material having a lower specific heat than that of the ferrite magnets is used for the rotor core.
 6. The motor of a compressor according to claim 4, wherein the holes penetrate both end faces of the rotor core.
 7. A refrigeration cycle apparatus comprising the compressor according to claim
 4. 